Originally Posted by
Academic
As you say, you have to pick up your bags at YYZ then go to the Connections Desk. The you leave Customs you can simply walk out of the main door rather than going to the CD. If you don't complain that your bags didn't make it to YOW I don't think they're going to come after you. In fact, they won't know what has happened to the bag except that it was offloaded at YYZ.
I'm assuming this is your intention but unless you plan on trying to co-ordinate pushing a roller to your waiting brother through the doors while you stay 'airside' you'll need to head upstairs (assuming you're staying in T1) and re-clear security.
Unknown where your brother is flying, but if it's not domestic remember you'll be going through to different seats of gates.
And this should go without saying but your brother will be asking if he packed the bag himself when checking it in for his flight; and there is no guarantee you flight won't be late. 5 hours
should be enough, but bear in mind bag drop off times at YYZ based on where he's flying.