'How many versions of Blu are there?!'

Many.

'Which is the most dangerous?'

BluDOS. She is programmed to send out DOS or DDOS commands to enemy intelligence. If you get near her, she attacks as a backup defense program.

How about we dont comment on my stupid little thing up there and just accept that this is the most dangerous version of Blu.

BluDOS and all the other Blu’s (c) Me

Portal and Portal 2 (c) Valve