No, seriously. Hear me out:
- Both rose to become leaders of the Horde via their own secretive influence. With Gul'dan, it was the creation of the Shadow Council and utilizing Blackhand as his puppet figurehead. With Sylvanas, it was the Jailer having Mueh'zala whisper to Vol'jin on his deathbed.
- Both massacred countless members of both the Alliance and the Horde (even going so far as to kill children and infants) in order to fuel the power of their dark masters, those being Kil'jaeden / Sargeras and the Jailer respectively.
- Both held no true loyalty to the Horde, and only sought to further their own agenda regarding themselves and their own fate. Even those closest to them and those within their inner circle were ultimately expendable.
- Both faithfully served said masters up until the point at which the relationship was no longer beneficial to them, where they then betrayed said masters and were punished as a result. With Gul'dan, he split from the Horde and tried going after the Tomb of Sargeras, to which he was torn apart by demons. With Sylvanas, she betrayed the Jailer after figuring out he was just like the Lich King, and subsequently was forcefully reunited with her soul before being left to the mercy of the heroes.
With those similarities being drawn... Why the hell are we even considering giving Sylvanas a shred of mercy, when we would never do the same for someone like Gul'dan?