Difficulty:
EasyThis is earned for thanking your partner after reviving you or giving you an item with
.
There appears to be some disagreement about when this should unlock, but if you play on your own and thank Sheva
directly after she revives you from near death, heals you, or gives you items (you have to request them first) you should get this before the end of your first playthrough.
You can force this by slashing a transformer at the end of the first mission until you're dying and letting Sheva heal you multiple times. Just remember to thank her right after and load her with health items before you attempt this.
Note: Chris will say "Thanks" if you're thanking her in time, but if you do it too late he'll just shout "Come on".