So, you want a badass animal companion to fight side-by-side with the rest of the party? Well, get one of the players to put the relevant species under “race” on his character sheet.
And no, I am not talking about beastmen or catfolk or some other anthropomorphic fantasy races, I am talking about actual honest animals. Come on, it’s not like there are no precedents for this in fantasy fiction of all stripes, whether all manner of birds (and other beasts) from Middle-Earth, the casts of Beasts of Burden, Felidae or WE3, or the heroes of the first Beastmaster movie (okay, there was a token human there, too).
But instead of putting together another game where everyone plays as an animal on some mystical journey or mission, just make up some stats for animal “races” to build your character with. Can’t be much more difficult than inventing yet another flavour of elves or dwarves for your campaign setting. How about magpies for D&D?
Ability Score Increase. Wisdom +2
Age. Less than 50 years
Alignment. Leans chaotic
Speed. 5 ft hopping, 60 ft flying
Keen senses. As elf
Speak with Small Beasts. As forest gnome
Thiefing Bird. Proficient in Sleight of Hand
Languages. Can understand Common and one extra language
Or perhaps a trusty Doberman to accompany as a (non-badge carrying) member of your operative squad in SLA Industries?
Unarmed Combat (STR) Rank 1, Running (PHYS) Rank 1, Tracking (DIA) Rank 2, Intimdation (DIA) Rank 2, Detect (CONC) Rank 1, Survival (KNOW) Rank 1
Just remember the new guys have to make do without hands.