Sorcerer in training
Would The Outlaw of Torn
by Edgar Rice Burroughs fit here?
A pissed-off retainer/swordplay teacher kidnaps the king's son and raises him as the worst outlaw he can. (Luckily, a local priest teaches the boy positive qualities.) The evil teacher's plan is to eventually have the prince hung, and reveal the distinctive birthmark on the young man's chest, thus proving his identity and bloodline, right before the execution. The teacher does this because the king -not the prince- took out a fit of anger on the teacher. (The prince was three at the time.) The goal was to humiliate the king.
Will note, the prince/outlaw is in his late teens/early twenties when the plan comes to fruition -and then the bad guy dies after revealing him. So he's not around to see the impossible tastes-like-diabetes Happy Ending.
Coming back to where you started is not the same as never leaving. -Terry Pratchett
It seems to me like these examples are one of TWO tropes: 1) killing an innocent, no matter how, in the quest for revenge against another or 2) an ironic killing (or injury) of someone in a particular role toward the enemy, specifically because the enemy killed someone in a similar role toward the avenger (e.g.—I'll kill your innocent mother because you killed mine).
The latter trope would be a more specific case of the former. But the way this trope page is set up, only #2 should be here.