New Kitten Hissing at Resident Kitten?

We've had our resident kitten for just over three months now. He is five months old. After the death of his litter mate, we have introduced a new kitten to the household.

The problem is, he seems fine and wants to play, following her around and licking her, but the new kitten doesn't want any of it. She is hissing, and growling and then eventually running away everytime he comes close.

Earlier this evening they both fell asleep next to me, (on opposite sides) and whilst they were sleeping I moved them together, he stretched out on her whilst she was asleep, and she stretched out and used him as a pillow. Then they one by one moved to the bottom of the bed (as I figured the television was too loud), and she positioned herself next to him, head on his fluffy white back again as a pillow.

She then woke up, realised what had happened, look confused that she'd obviously done it in slumber, growled, hissed, and ran away. Now she won't go near him without reverting back to the hissing and growling, but she curls up next to me and purrs and headbutts me still.

Help!

By John