“'You're worth twelve of Malfoy,' Harry said [to Neville]. 'The Sorting Hat chose you for Gryffindor, didn't it? And where's Malfoy? In stinking Slytherin.'”—Harry Potter and the Philosopher’s Stone, Chapter 13
“'We were all in the D.A. together,' said Neville quietly. 'It was all supposed to be about fighting You-Know-Who, wasn't it? And this is the first chance we've had to do something real – or was that all just a game or something?'
‘No – of course it wasn’t –’ said Harry impatiently.
‘Then we should come too,’ said Neville simply. ‘We want to help.’”—Harry Potter and the Order of the Phoenix, Chapter 33