When word reached Garithos that the blood elves had allied with the naga, he was disgusted. from wilkinson's blog

After all the destruction and the demise of his father the King, the Prince Kael'thas Sunstrider was left with the option of scraping his way through the remnants of his people and find help elsewhere. The consequences that came with losing the Sunwell were taking a heavy burden on wow classic tbc gold his fellow citizens too Mana withdrawals were threatening to turn them all mad with hunger for magic. Kael'thas had renamed his people blood elves or sin'dorei following the aftermath of this devastation. The survivors of Warcraft's Scourge invasion of Quel'thalas set off into the remnants of Lordaeron but Arthas had reduced the majority of it to rubble already, and few remained to pick up the pieces.

A small portion of Warcraft's Alliance persevered in Lordaeron in that period, because most of its soldiers and all of its experienced leaders were still fighting the Burning Legion a continent away. Therefore, the blood elves were confronted by a person who would prove to be the catalyst in the end that shattered any affection for the Alliance they left behind. Othmar Garithos is a highly-ranking officer who found himself in charge of the entirety of the Alliance troops that remained in Lordaeron but not by merit, but merely by the need to be desperate. He was a tough racist, xenophobic, as well as a rude man, who believed that the entire range races in World of Warcraft's races as being less important than humans.

Kael'thas pleaded with Garithos to help However, the nepotistically-promoted Grand Marshal held nothing but disdain for the traumatized blood elves. He refused to let them battle side-by-side with his soldiers against the Scourge. Instead, Kael'thas sent his forces on suicide missions against the undead of Warcraft hoping that they would not come back. Without a choice, Kael was willing to accept help from Naga, the snake-like creatures who hail from the ocean. When word reached Garithos that the blood elves had allied with the naga, he was disgusted.

Even though it was evident that sin'dorei only joined blades with the naga to prevent their own massacre, Garithos used it as an excuse to put them to death because of deceit. The blood elves from WoW's Azeroth were imprisoned and could have been executed had it weren't for Lady Vashj who is head of the group, joining forces together with Illidan Stormrage and Akama to save them all. The sin'dorei escaped Garithos with the  cheap wow classic tbc gold Scourge and subsequently followed Illidan, who promised they could thwart their mana depletion with fel as a source of power. Kael'thas enthusiastically agreed and led his people into a world in which they would finally have the security and power they deserved.