There are a few feats in my Rhunaria homebrew that beef up familiars.
One of the PCs has taken Divine Familiar and Greater Divine Familiar, so far, and may take another feat to make his familiar more survivable. He gained Altania L'Salle as a divine patron after a strange dream in the Bloodgrass Fields, in which he expressed his sorrow and outrage at the emotional and spiritual wounds inflicted upon the spirits of the Fields, changing them to their present form and name, as the spirits lashed out at any mortal travelers upon the Fields. He vowed to find a way to restore the Summer Fields and help the nature spirits there, and so Altania gave him a riddle that would guide him part of the way, along with her blessings in the endeavor. A while later, when next he leveled up and gained a feat, he took Divine Familiar. He's now heading towards entering the Spiritbond Exemplar prestige class, which improves the usefulness and resilience of animal companions or familiars or special mounts, but hasn't quite taken it yet, because I haven't quite finished typing all the details of its abilities yet.
Feats in spoiler block.
[sblock]Adept Trainer (General)
You have developed great skill in training some creatures, improving their physique and their ability to follow commands. Part of your secret is what you have learned through interacting with a special companion beast.
Prerequisites: Handle Animal 5+ ranks, character level 3rd+, Cha 13+, must possess an Animal Companion or Familiar or Special Mount.
Benefits: You gain +1 on all Handle Animal checks. Animal Empathy becomes a permanent class skill for you, with all classes you have and may later gain. In addition, you train creatures especially well, making them more physically fit and mentally capable. Any animals or beasts you train will naturally gain +2 Constitution after a year's worth of training, and at the same time they will learn 1 bonus trick. Animal companions you maintain also receive a +1 competence bonus to natural weapon damage rolls, so long as they know you are nearby; this bonus is not dependant on time spent training. Any familiars of yours will naturally gain +1 to their maximum hit points per hit die they effectively have, after you have trained them for a year. Regardless of training, your familiars gain a +1 bonus on all saving throws. Your special mount naturally gains +2 Wisdom and +2 Constitution after a year of training by you. Lastly, regardless of training, your special mount gains the bonus feats of Spring Attack, Mobility, and Blind-Fight, benefitting from them regardless of prerequisites.
Toughen Familiar (General)
You have used your magical talents to improve the resiliency of your familiar.
Prerequisites: Must have summoned a familiar and have it present at the time you would gain this feat.
Benefits: Your familiar gains +2 hit points per point of Constitution it has, to a maximum of double your effective class level for purposes of familiar benefits. As you gain or lose levels, or as your familiar gains higher or lower Constitution, this benefit may retroactively improve or diminish as appropriate. The familiar also henceforth gains Damage Reduction 1/- which functions like that of a barbarian. However, this DR only operates while the familiar is within 1 mile of you and on the same plane of existence.
Scion Feats: A rarely-available and special type of feat in Rhunaria is the Scion feat, granted by special divine patronage of some sort. Characters cannot gain Scion feats unless special circumstances grant them such a divine patron, and they only retain such feats as long as their divine patron continues to support them. Scion feats are much more potent than ordinary feats, generally of an order one or two magnitudes greater, sometimes slightly more, but since they all require several hours of prayer each week, limiting time for training and other supplications, no more than 7 Scion feats may be possessed by any given character. Access to Scion feats should not be taken lightly, and should be allowed only after consideration by the DM, who may limit which Scion feats are available. Regardless, any character with Scion feats is likely to be required by their divine patron to perform some quests or tasks for them on occasion, moreso if the character possesses multiple Scion feats. No Scion feat should be selectable more than once, nor should it be available without some mental or magical skill.
Divine Familiar (Scion)
Your divine patron has provided you with the power to bless your familiar with divine resilience, so long as you spend 4 hours each week in prayer and homage to the divine patron. This is in addition to any other time you already spend on such activities each week.
Prerequisites: Familiar, Wis or Cha 13+, ability to cast at least one 1st-level arcane spell each day, divine patron must have the Magic domain.
Benefits: Your familiar gains a deflection bonus to AC equal to your Wisdom or Charisma modifier, whichever is higher. Your familiar also gains an equal luck bonus on saving throws. Lastly, your familiar acquires Damage Reduction 2/-, which functions like that of a Barbarian.
Greater Divine Familiar (Scion)
Your divine patron has granted even greater defensive blessings to your familiar, so long as you spend 4 hours each week in prayer and homage to the divine patron. This is in addition to any other time you already spend on such activities each week.
Prerequisites: Familiar, Wis or Cha 17+, Divine Familiar, ability to cast at least one 5th-level arcane spell each day, divine patron must have the Magic domain.
Benefits: Increase the AC and saving throw bonuses of the Divine Familiar feat each by +1. Also, improve the Damage Reduction of that feat to DR 3/-. In addition, your familiar gains the Slippery Mind ability, as per the same ability of Rogues. Lastly, up to three times per day, you can expend a 5th-level or higher arcane spell slot in order to grant your familiar 2 temporary hit points per spell level, or instead heal your familiar of up to 2 damage per spell level. These particular temporary hit points stack with each other, and with other sources of temporary hit points. Granting this healing or these temporary hit points to your familiar is a supernatural ability that takes a standard action to activate, but does not provoke attacks of opportunity. Any temporary hit points left from a use of this ability fade away after 1 hour. The familiar must be within 1 mile of you in order to initially receive the healing or temporary hit points.
Superior Divine Familiar (Scion)
Your divine patron has granted still-mightier blessings to protect your familiar, so long as you spend 4 hours each week in prayer and homage to the divine patron. This is in addition to any other time you already spend on such activities each week.
Prerequisites: Familiar, Wis or Cha 19+, Divine Familiar, ability to cast at least one 7th-level arcane spell each day, divine patron must have the Magic domain.
Benefits: The AC and saving throw bonuses of the Divine Familiar feat are each increased by +1. Additionally, your familiar's Damage Reduction from the Divine Familiar and Greater Divine Familiar feats is improved to a total of DR 5/-. Furthermore, your familiar gains the Mettle ability, as per a Sohei.[/sblock]
Lessee.....for a different setting, I have a sorcerer-replacement called the Magus, and its familiar is just a bit different and improved.....the extra few familiar benefits could be used for sorcerers, wizards, and adepts.
Magus familiar stuff in spoiler block.
[sblock]Summon Familiar: A magus can call a familiar, which is different from that of a wizard’s or sorcerer’s familiar. Doing so takes a day and uses up magical materials that cost 100 gp. A familiar is a magical, unusually tough, and intelligent version of a small animal. It is a magical beast, not an animal. The magus chooses the type of familiar he gets. As the magus increases in level, his familiar also increases in power. If the familiar dies, or if the magus chooses to dismiss it, the magus must attempt a Fortitude saving throw against DC 15. If the saving throw fails, the magus loses 200 experience points per class level. A successful saving throw reduces the loss to half that amount. However, a magus’ experience point total can never go below zero as the result of a familiar’s demise. A slain or dismissed familiar cannot be replaced for a year and a day. Slain familiars can be raised from the dead just as characters can be, but do not lose levels or Constitution points when this happy event occurs. A magus’ familiar is just like a sorcerer’s or wizard’s familiar, except that the animals the magus can choose as familiars are somewhat different and more powerful, gaining a few additional traits. A magus’ familiar can be chosen from among the following special creatures.
Spectral Bat: Same as bat familiar, but has +4 higher Strength, and also grants master +6 to Listen.
Spectral Lynx: Same as cat familiar, but has +2 higher Strength and Dexterity, also has a +4 racial bonus on Listen checks, and also grants master +4 to Listen and Move Silently instead of just +2 Move Silently.
Spectral Falcon: Same as hawk familiar, but has +2 higher Strength and Dexterity, and also grants master +6 to Spot checks in any light at least so bright as torchlight.
Spectral Owl: Same as owl familiar, but has +2 higher Strength and Dexterity, and also grants master +2 to Concentration.
Spectral Fox: Same as rat familiar, but has +4 higher Strength, and also grants master +4 to Fortitude instead of just +2 to Fortitude.
Spectral Raven: Same as raven familiar, but has +4 higher Strength, and also grants master +2 to Search and Spot.
Spectral Serpent: Same as tiny snake familiar, but has +4 higher Strength, and also grants master +2 to Hide and Move Silently.
Spectral Salamander: Same as toad familiar, but has +4 higher Dexterity, and also grants master +2 to Swim and Fortitude, as well as granting its master +6 hit points, instead of granting its master +2 Constitution.
Spectral Ferret: Same as weasel familiar, but has +2 higher Strength and Dexterity, and also grants master +4 to Reflex instead of just +2 to Reflex.
Familiar's Spirit: All magus familiars are strong in spirit, allowing them to apply any armor, natural armor, and enhancement AC bonuses of theirs against attacks from incorporeal creatures. They are also able to strike incorporeal creatures as though wielding magical weapons, regardless of what attacks they use, and they ignore the 50% chance of failing to affect incorporeal creatures with weapons, natural weapons, unarmed strikes, and so on. Additionally, the familiar gains immunity to fear effects.
Familiar's Augmentation: At 9th-level, the magus’ familiar magically develops increased capabilities, permanently granting the familiar a +2 inherant bonus to all six ability scores, and also granting the familiar a permanent +3 enhancement bonus to attack and damage with its natural weapons and unarmed strikes, as well as a permanent +3 enhancement bonus to the familiar's natural armor to AC. Also, the familiar's enhancement bonus to natural weapons and unarmed strikes also carries over to grapple check damage, melee touch attack rolls, and other non-weapon melee attack rolls, but does not affect actual grapple checks nor the damage of other melee attacks (only unarmed strike, natural weapon, and grapple check damage).
Familiar's Spellcasting: Upon reaching 15th-level, the magus’ familiar gains the ability to cast spells. The familiar then casts spells just like its magus master does, knowing all of its master's magus spells up to the 3rd spell level and able to cast any of those spells just like the magus, but expending its own Vitality and Health instead. Magus familiars expend an additional 2 Vitality per magus spell they cast, and the familiar uses its own Intelligence score for determining save DCs, while the familiar also counts as a caster of its master’s caster level. The familiar does not gain any of the magus’ other feats, class features, or abilities, except that at 19th-level the familiar can henceforth use any of its master's feats that apply to magus spellcasting, except for item creation feats.
SIDENOTE: With the normal spellcasting system used instead, a magus of 15th-level or higher has a familiar who instead casts spell as per a 6th-level sorcerer, but using Intelligence as the key ability score for spellcasting, and limited to only casting spells of up to 3rd-level. However, the familiar's spells known are simply all of the magus' spells known of up to 3rd-level, from the magus class.[/sblock]
