... He's so lovely I could squeeeeeeeze him!
He's lived with us (50/50) since he was 3 and my eldest was nearly 2 and he's a smashing lad. He's nearly 15 now and he and his step-brother (my ds) are so close we forget they're not 'proper' brothers. In fact, I love him so much that I forget I didn't give birth to him sometimes 
We have 5 DC now and although we have the usual ups and downs with kids they're all fantastic and our blended family runs along nicely.
Thought I'd just add a positive thread about step DCs, sometimes situations DO work out for the best when families join together.