Deducing the Design

After Hannibal and Will fall, they move to London and try to live a normal life there. Although, normal means hiding murders in this case.
Sherlock accidentally runs into the pair while they're looking at 221c. He was on his way to a new case, which he doesn't know was done by Hannibal.
Hannibal is curious about the detective and his companion, so he decides to live close to 221b. Sherlock is also inquisitive of Hannibal and starts to stalk his every move. Their meeting is inevitable, but when it will happen is not known.