Yes, the one who took Nil was Evan. During Nil escape to the north, it passed Evan's group. Evan who noticed there was a beastmen who ran fast ahead decided to give a chase after Nil.
However, Evan failed to catch up with Nil's speed. Nil was just too fast, but Nil was running straight ahead. So it was easy for Evan trailed Nil. Moreover, he noticed Nil was heavily injured, so Evan just followed the trail. And then, Evan found Nil collapsed.
Considering Nil's speed and the information appeared in his eyes, Evan decided to take Nil as its subordinate. A dying Divine Grade Beastmen, it was easy to subdue, it was the same as a free strong subordinate.
Sure enough, the desperate Nil immediately established a contract instantly soon after he offered it. It could be said a jackpot for Evan, taking a Divine Grade Beastmen as a subordinate.