Best charcter to duo with a Dark/Thermal corruptor?

My girlfriend wants to run a level-pact group with me and she already knows she wants to play a Dark/Thermal corruptor. My question is what's a good melee toon to run along as her meat shield? I'm already making a SS/WP Brute as my solo toon so I don't really want to repeat either of those two power sets.

I know I want a brute, tank, or scrapper, just unsure which.

I know I want a resistance based set since her buffs will make me that much nastier, plus her dark attacks will make them hit me even less. Maybe invulnerability? I am kinda fond of that one.

Completely unsure what offense set to run for the moment. Maybe Dark Melee?

Any recommendations?

DM/Fire or Fire/Dark Brute or Scrapper. Fits thematically to what she's running, has resistance shields which will benefit from her shields and both are very good combos.