Another thing I’d add to my take on the BM.
The subclass features shouldn’t all revolve around the pet, as such. Give the BM ranger teamwork benefits, let them hunt as the leader of a pack, and that will naturally dovetail with having a beast companion. Let them spend spell slots to include more than one ally, but make the at will benefits have a small boost when used with a beast.
I know this is way old, but I just recently started playing a 5E BM Ranger, and was browsing around for thoughts and possible homebrew fixes as my pet sits engulfed by a plant monster with 2 HP left.
I like this idea of the Ranger's abilities being more generalized. If I understand correctly, the effect would be that I could, essentially, do a combined attack with my pet or with another party member, with that party member using a basic from of whatever attach they might normally do?
Most of all though, while I haven't read every page here, I am wondering if I am just missing something, because it really all doesn't seem like that difficult of a fix for me.
As far as damage and function balance, take a page from vanilla WoW and have a bit more variety as far as pets and special pet abilities. Have families of pets, and each family has some ability like a charge or pounce or swoop. Each pet has at most two of these special abilities, and they can be used in a combe with the pet's basic attack, sort of like Favored Foe is part of the Ranger's attack, but like Favored For, also have "charges" that are replenished on a long rest.
So, at that point, offensively, the pet is just like getting an extra flavor spell or ability that adds something to the dynamic of fights. Nothing huge, but like the charge from Tasha's, something functional. To keep balance, these abilities could simply be watered-down version of existing spells that a class with a similar fighting style to that animal family has.
So, for instance, a dragon pet could have a fire attack that hits about as hard as a fire cantrip.|
But most of all, I don't get why the the defensive element seems so difficult, and this is where I worry most I'm just missing something obvious.
Cats, wolves, and the like should have incredibly high dex and AC on-par with the ranger's own. If the pet only hits about as hard as the attack they are replacing, why would this ever be a problem? You are basically getting a Ranger split in two, half melee and half ranged. Have these dextrous beasts attack 2-3 times each time they attack, but with something like a d4 and maybe half the PC's proficiency bonus as a modifier, so better chance they land a hit, but less damage when they do unless they just get a lucky series of roles.
Bears and the like should have decent AC -- but not as high as dextrous animals -- mammoth health pools that fit the reality of trying to take down a flipping bear, and roll a single d8 or d10 attack with minimal modifiers.
As for HP, and going back to the OP's original thoughts, again there's a pretty straightforward and simple solution that already exists in plenty of games in relation to pet classes. DND is not the only game in the world where squishy pets create problems for players, emotional and otherwise.
Simply give the ranger a magical bond with the pet, such that any time the pet takes damage, without using a reaction or expending anything, the ranger can choose to take half of the damage for the pet. It only goes one way, so the ranger can't slough off damage the PC takes onto the pet, but it keeps the pet in the fight without making the ranger any more powerful. Also, make feats such as mobile apply to the pet as well, enabling it to avoid opportunity attacks and do a kind of run in, quick strike, and run out as just a normal maneuver.
There you go. The pet doesn't get squashed by a couple lucky hits and can actually be sent into melee, and the ranger isn't getting power like they are playing two PCs at once.
