Teen Wolf, Season 3

Peter:
I've heard it's something only an alpha can do, and with good reason.

Derek:
Which is?

Peter:
You know normal wolves never abandon an injured member of the pack. They care for it. They bring it food from a kill, and then regurgitate it into the mouth of the injured wolf. They even give it physical and emotional comfort by intensely grooming it. In a way, they can do more than just ease pain. They can be instrumental in healing their own.

Derek:
If you're trying to tell me I can save her, just tell me.

Peter:
I'm telling you... I've heard it's possible.

Derek:
How?

Peter:
It's that spark of power that makes you an alpha. When you take her pain, she draws on the power that provides you with those special gifts. The power that heightens your senses, your strength. The power that transforms your body. As an alpha, you have that bit of extra, that spark that intensifies the color of your eyes from a bright yellow into a searing red.

Derek:
If I can save her...

Peter:
If.

Derek:
If?

Peter:
I didn't say it works every time. It could just as easily kill you.

Derek:
How do I do it? By taking her pain?

Peter:
And then some. Because there's a cost.