Jallek Lenkin is an NPC involved in the Spirit of Summer quest. He is one of the three spirits that traps the Spirit Beast. The other spirits are Meranek Thanatos and Erik Bonde. Jallek and Meranek used to work for Erik as farmhands.
During the Summer's End quest, Jallek Lenkin explains to players how to hurt the Dark Energy Core in the Spirit Beast's chest. He is put to rest at the end of the quest.
During the Spirit of Summer quest he helps you learn emote communication when he talks to Meranek Thanatos.