How do you get portal 2 for free for the PC

This answer is for informational purposes only. You CAN download it via torrent, which you would find on a torrent site, and use a torrent downloading program, which uses p2p technology for transfer.

Upsides:
Free Software
Potentially quick downloads

Downsides:
If the software isn't supposed to be free, downloading via this method is illegal, punishable by large fines, and years in prison.
Potential of viruses
Potentially very slow downloads.