While I totally understand the appeal of imagening post-captivity Gwindor & Maedhros as friendly & bonding over their trauma if they ever met because Ulmo knows both poor boys deserve group therapy and an understanding friend, one thing that must be remembered about Nirnaeth Arnoediad is that in that battle the plan was that Maedhros would march with all his might in the open to lure all the forces of Morgoth out, and only then Fingon would attack with his army from the other side and Melkor's army would be crushed between them. But the orcs tortured & then killed Gwindor's brother, Gelmir in front of Fingon's army so Gwindor, despite Fingon's many warnings & beggings for everyone to keep their cool in front of the obvious bait, lost his calm and in a fit of rage lunged forward and forced Fingon's army to attack full force before Maedhros' army was anywhere near.
And I think most probably for Maedhros causing Fingon's death however indirectly, would take precedence over sympathy, Gwindor paying dearly for his mistake, Gwindor's rage at that moment being understandable, Maedhros himself being an older brother, etc...even in his best days, and pre-Nirnaeth Maedhros was far from his best days. (Pre-Nirnaeth Maedhros would laugh in the face of Thingol's obvious insult and keep his cool and invite others to do so, too, he would attend feasts, go hunting with his cousin & brother, was hopeful, and would keep lines on the borders that would have been lost in the hands of anyone else or take back what has already been lost, he would plan to defeat Melkor, he would never kinslay, post-Nirnaeth Maedhros kin-slayed thrice, regretted his kin slaying, felt the burden of the oath & kin-slayed again, lost his brothers, always talked grimly & had lost all hope.)
(And I think Maedhros blames himself for Fingon's death, too. Because Nirnaeth was his project, because the traitors were in his army, because he fell for the house of Ulfang's deceit and didn't arrive on time to save Fingon, and most importantly because after the Nirnaeth the Noldor clearly remembered and believed the Doom of Mandos to have named that battle the battle of unnumbered tears, and part of that doom was that "On the House of FĂ«anor the wrath of the Valar lieth from the West unto the uttermost East, and upon all that will follow them it shall be laid also." And Fingon sure followed him. And when he couldn't kick his own ass, he could kick Gwindor's ass.)
So I think if Maedhros ever saw Post-captivity Gwindor he would somehow remind him that he has managed to get the High King of the Noldor killed. He should be proud of himself. Melkor had a price on the High King's head for centuries and didn't manage to do what Gwindor did. To which Gwindor (who is quite an upfront person with notable truth bombs like "The doom lies in yourself, not in your name.", "fuck the day I met you, Turn Turambar <3", Turin's identity reveal to Finduilas) would reply that not every brother is like Maedhros' brothers to see their brother tortured in the hands of the enemy and still stand aside and do nothing.
And then either they would remember that they're noble lords of the Noldor and can't beat the shit out of each other and can at most only exchange biting words but still with acceptable, respectable vocabulary, and storm off, OR they'd beat the shit out of each other.
But yeah, no group therapy for them.
