So Zaros can disengage Seren’s modifications to the alliance he desires, but it doesn’t alter the truth that Seren’s faction’s now the OSRS gold one who has Saradomin’s daughter, therefore she is the left handed one who will acknowledgment her to him and match the pact. So Seren wins that you either way.
And Zamorak includes a modified accord entirely. With Armadyl and Saradomin’s pacts, neither bisected has been accomplished yet. Giving Zaros the Bedrock comes aboriginal for each of these, and afresh Zaros performs with his activity — something which Seren can footfall in and above.
But with Zamorak, it is the extra way round. Zaros was the one who performed his action first, in daring the Cheap Runescape gold</a last ritual at Children of Mah. Therefore the pact's currently bisected finish by the time of Endgame.
There is annihilation for Seren to yield over from Zaros, since he's already done his bit. She doesn't even attempt, adequate or otherwise. All that's larboard is for Zamorak to play his allotment — and about-face within the Stone.