Be careful what you wish for...

[The Elf-warrior]

I wish Fingolfin would have defeated Melkor

Your wish is granted. But Sauron became the new Dark Lord and made a Ring of Power in Thangorodrim and Thingol asked Beren for Sauron's Ring instead of a Silmaril. Beren reluctantly agreed and was successful and after a great mental struggle gave the Ring to Thingol. One night Beleg, at Melian's pleading, took the Ring from Thingol and flew on an Eagle to Thangorodrim and refused to destroy the Ring. The Eagle then dropped Beleg into Thangorodrim as they previously agreed upon. Meanwhile Thingol killed Melian in a rage and was killed by one of her servants himself. Also Gothmog became the new Dark Lord and ordered a successful assault upon Doriath. This became the Battle of Unnumbered tears.

I wish that Nienor hadn't commited suicide.