He didn't necessarily like the idea of having a soulmate. He felt as though romance would only throw his plans off. It wasn't until he saw how loyal you were to him. Whether it was the effect of the bond or your genuine feelings, he felt like he could use that. You had a decent quirk and he thought you were pretty intelligent. So he used you in his plans.

"We're doing this for us. If we accomplish this, they'll be nothing standing between us. So, will you help me?"