Spoiler Alert!!!!
So I just watch the leak of Lars' Head (Preview) MASSIVE SPOILERS 
And I think the reason Steven can Fuse with Connie is because he Healed her with his tears earlier. This could have changed her DNA and made her "gem compatible" or at least compatible with Steven. This explains why Stevonnie doesn't have 4 eyes and as per the leak about Stars (Steven+Lars) is fast approching. What do you guys think? Does my theory hold water? Also my Stars #hype is unreal right now!
