Feathered Souls' Aura Clones

Use the bioenergetic crystal to make aura clones of Alk Two-Arrows, Phell Sharp-Sighted and Koati Close-Lipped, then return the crystal to the Brainiac Family in the League Settlement.

We committed a serious error with that expedition. Everyone is avoiding Silvia now. What on earth got into us... Oh well, it's all over now. Nobody was hurt, and that's the main thing. Was there something you wanted to discuss?
So, there is an evil spirit around? That's not good... though not so scary, either.
We'll need the evil spirit's aura clone to catch him. We had some possessed around here, didn't we? Oh, just one? That's enough, we'll just have to work a bit harder. Thing is, we don't specialize in aviak auras, so we'll need several samples.
Here's a crystal for you - it's new, virginally pure and bioenergetic. Give it to the possessed fellow to hold, and his aura will imprint on the crystal, along with the imprint of the evil spirit. But that's not enough, we'll also have to split them up somehow. For that we'll need imprints of aviaks' pure auras, the ones that haven't been affected by the evil spirit. To make it easier for us, make sure that one of them is the same age as the possessed, while the other is a bit older. When you obtain all three clones, bring the crystal to us. We'll identify the evildoer.

Be careful, don't break the crystal! We have less than two boxes of them left.

Let's have a look. Oh, I see, that's our martyr. Look at that - a clear imprint, a strong trace of another's influence. The second... There, we can see a trace of something alien too, but very faint - they were probably in contact with the possessed. The third one is pure aviak. So that's what they're really like! Now we just need to isolate the spirit's aura and we are done. One second...
We have four imprints here. Where did the fourth one come from? Guess! You, obviously! But that's not the curious part. The curious part is this: why is the evil spirit's aura so similar to yours?