(was meant to be you're... always messing up titles)
Loki is the last person Clint wants to see after all that happened, so when Loki shows up at his place looking ready to destroy him, and he ends up causing Clint some serious injures. Though upon realizing Clint could die Loki knows he must stop him from dying as he needs him for something, though later on Loki starts to soften.

 [img=http://images5.fanpop.com/image/photos/29500000/Loki-in-Avengers-loki-thor-2011-29593928-452-600.jpg] 
Loki played by me :D