Solomon enjoys having power...He especially enjoys having the power to bend demons to his will...He wanted to break you in a nice way...He first saw you in the halls just minding your own business, casually playing with your powers...

So naturally, he made a pact with you...It didn't take much convincing because you were surprisingly willing so now he wants to see how far he can push you...Summoning you every single day to do something new...He enjoys when you finally snap and attack him...