A Displaced Beast

I have been having trouble coming up with stuff for my current fics so I decided to try something new. It hits me like a super sledge... a Displaced deathclaw. Something I would really like to try is a method of powering up like Digimon (from the anime) into alternate forms. (Referencing Fallout 4 (sadly the only game I'm familiar with)) I would have the regular deathclaw as a base, but I'm having trouble making a definite "chain of evolution." I know that the "Savage deathclaw" would be a berserker form and "Mythic deathclaw" for a last resort. another issue is who the main antagonist would be. I'm not very familiar with anything previous to Fallout 4 and I don't want to upset any fans. I would appreciate any help. Thanks.