More Moody Madness

[adatole]

No: HPFGUIDX 36198

Something I have never been able to work out about the whole 
GoF "Crouch is Mad Eye Moody" thing:

Why did he help any of the kids at all? I can (barely) understand his 
helping Harry to get to the end of the TriWizard tournament so that 
he could touch the portkey and get to Voldemort (which is a huge 
stretch when there were so many other ways to do this - just take 
Harry out for icecream in Hogsmead and then portkey him there. Or 
forget the portkey. Knock him cold and carry him. Whatever.)

ahem.

My question though, is why Moody worked with Harry so many times on 
the curses, why he worked with Harry until it was nearly guarenteed 
that he'd be able to resist Voldemort?

And why did he give Neville those books, inspiring the kid to work 
harder to excel. Why not laugh at the feeble spawn of the parents he 
had killed, and leave Neville to wallow another year?

It seems totally out of character for Crouch, even mascarading as 
Moody. All Crouch needed was to be mediocre - teach the course book, 
don't cover extras, keep a low profile. Befriend Harry along the way 
only as much as it would help keep him in the game.

Any thoughts are appreciated.
Leon