I like the idea of familiar development. Below is the system I'm using for my game (note: I also use a variant arcane caster whose familiar starts off a little weaker then the wizard core familiar)
FAMILIAR INCREASE CHOICES
2nd Pair of Eyes: The familiar can take 10 to assist other to aid you in all search, listen, and spot checks.
2nd Thought: The familiar can maintain control of a spell 1/3 the caster level of the master for up to LV/3 rounds per spell cast. Requires 2nd Pair of Eyes and Eye to Eye or Scry Familiar.
Come to Me: 1/day as a standard action, teleport your familiar up to 300’ + 10’/LV, to your current location.
Eye to Eye: LV/5 a day, sense through your familiar for LV minutes (dismissable). Requires 2nd Pair of Eyes
Feral Link: As per Link of Fury, except it does d6/(spell LV sacrificed) damage. Requires Link of Fury.
Fist of My Fist: As Hand of My Hand except you may sacrifice the spell without touching your familiar, up to a range of 100’ + 10’/LV. Requires Hand of my Hand
Hand of My Hand: By touching your familiar and sacrificing a touch attack spell, you grant your familiar that spell effect as if it had cast it.
Link of Fury: You may sacrifice a spell as a quickened action, adding d3/(spell LV sacrificed) damage to a single attack of your familiar. The additional damage is weapon damage unless the spell sacrificed had an energy descriptor – if so, so to does the familiar's attack. Requires Hand of My Hand.
Of My Body: You may have spells you casts on yourself also affect the familiar 5’ of you. The spell effect on the familiar ends if it moves over 5’ away from you. You may target the familiar with spells with a target of ‘self’ or ‘you’
Scry Familiar: The Arcanist may scry on his familiar (as per the spell scrying: once per day. You may spontaneously cast this as a 3rd level spell to Scry on your familiar additional times.
Shield Companion: Sacrifice a spell to cast Shield Other as a move action. It can only be cast between you and your familiar, lasting a # of rounds = the level of the spell sacrificed. Requires Succor Companion.
Speak with Master: The familiar and master can communicate verbally with their own unique language.
Spell Resistance: Familiar gains spell resistance equal to the master’s level + 5.
Succor Companion: heal that sweet little pal of yours, you can sacrifice a spell/spell slot as a free action (limit 1 spell per round), healing, by touch, 1d3/spell LV damage. Requires Of My Body.
You could make these feats. In my game & with my class, the arcanist gains a familiar at 1st, gains one of the above free at 3rd, and every 4 levels thereafter.
The base arcanist familiar looks like this:
Natural Armor Adj: ½ + ½ caster level
HP: ½ Arcanist’s normal HP
HD: Arcanists HD
Intelligence: 5+ ½ caster level
Base Attack: as yours
Saves: as yours or +2/+2/+2 - whichever is better
Special: Alertness, improved evasion, empathic link, Speak with animals of its kind, and 1 of the above (that you meet the requirements for)
