In what Maedhros was re-embodied early and was sent back to Middle Earth on his volition with Glorfindel.

This isn't about what happened right then but years after Fall of Sauron when he still refused to return to Valinor.

He found a strange sapling at the shore of what remains of Cuiviénen.

He was going to die. The molten rocks would burn him just like the cursed gem in his palm did. Maybe less painfully but still being burnt hurt and Maedhros knew it. He intimately knew it from his time in Angband where Þauron burnt him often in frustration and to toy with him and his master burnt his skin even more often just to mock his ancestry. At least here he would pass on to Mandos and not linger in pain only to be sewed back together to be tortured again and again.

But it wasn't true for his next clear memory was of the same pain from which he escaped soon and half-mad entered the Girdle to never never leave till now.

A winter night in Himring. But inside the quarters where fire blazed in hearth was warmer, and not only from the fire or quilt.

Hastaina-marred, she was, they both were but with passage of time the pain should subside, shouldn't it?

In an AU where Huan fought Carcharoth much earlier and wasn't there to protect Beren and Luthien from Celegorm. It was the aftermath of it.

After Maedhros and Maglor stole the two silmarils and escaped Ëonwë's camp, Elrond and Elros had followed the two in secret. And when the two casted the gems in their respective resting places, the four of them woke up to a dark Arda, along with the cursed beloved gems.

Nothing was right in this Arda.