When playing the Chains or Freedom questline in SWTOR, you can unlock a secret bonus cutscene when entering the final Hideout of Lord Umbral on Mek-Sha.
To view the secret cutscene, you need to have Amity as your active companion when you first enter the Hideout and begin talking to Lord Umbral. As long as you do not attack him immediately during the Cutscene, Amity will chime in if you attempt to reason or converse with Lord Umbral instead of beginning the final battle!

It doesn’t matter what faction or quest choices you have made before, or even if you used a different companion for any of the prior quests in the series. As long as you enter the Hideout and talk to Lord Umbral with Amity as your active companion you will get the cutscene.