Alright, I've had some time to play with the Boon Companion, and there is definitely something buggy with it. First, I made a druid 6 with an ape companion, and got 42 hp and 19 ac for the companion "quick stats" that appear on the right hand side of the screen. Then, I dropped 4 levels of druid, and replaced it with 4 levels of fighter. I then selected boon companion, and selected druid. 42 hp, 19 ac. GTG. Here's where it starts to get interesting. If I select fighter for boon companion, I get 28 hp and 17 ac. Its as if Boon Companion is using 1/2 of the fighter levels to add to the druid companion. It does the same if I select Boon Companion (Druid), and then delete two levels in fighter.
So now I go back towards my original build, creating a new character and replacing the six levels of druid with six levels of sorcerer. I chose the arcane bloodline, and selected a cat familiar. I get 25 hp and an AC of 17 for the familiar. So, I deleted 4 of the levels of sorcerer (getting 9 hp, and an AC of 15 for the cat). Now I add 4 levels in fighter, and the familiar stats change to show the new hp. I now have 29 hp and AC 15. I select Boon Companion and am told that I can't take it, since I don't have an animal companion. Thing is, the feat in the book says I can take it if I have a familiar or a companion. One more thing to try...
I take wizard 6, cat familiar again, and get 13 hp, ac 17. Now I drop 4 levels of wizard, replace it with 4 levels of fighter, and get hp 17, ac 15 on the familiar.
Now, I understand the whole hp thing. The familiar's hp are half of the caster's hp, no matter what. Easy peasy. My problems are thus:
1. Boon Companion isn't acknowledging a familiar, only the animal companion. In the defense of the programmer, the feat says as much in the warning message when I take it. But, the feat in Seekers of Secrets says that it should apply to familiars as well. It appears to be working properly for druids but not for sorcerers or wizards.