An ally of the mortal realm, seemed, legitimate. But just how good was she, could she slaughter an angel, butcher a demon? It all needed to be tested. He needed the strongest allies he could find, would she cut it? Even if she didn't, he was sure she'd still be useful, she could help provide him with support in singular combat, what ever she chose. He didn't care, so long as she was willing be his friend and ally, he'd take it. 
"Sounds fine to me, but I'll have to asses your strength in battle, which means when we get the chance, you'll fight me, full on. If you're alright with it of course!" As he said this, he let fire emerge from his eyes, it was his favorite thing to do before a coming battle.