Actually it depends on which instance he tried to have Will killed. Because each time has a different reason. read more
In Shiizakana, Hannibal sent Randall Tier after Will for the mere reason of getting even with Will (and probably to see if Will would be able to kill him) as Will had sent Matthew Brown to kill Hannibal before. read more
One can assume that Fuller did not intend to kill off Hannibal and Will — they’ve come back from worse, after all. But the cliff jump makes an interpretation of the finale where the pair die together fitting; they tried to live without each other earlier in the season, but forever were clashing back into each other. read more