Extend the Bulwark (Feat)
You can bolster your ally's defenses by exposing yourself to harm.
Prerequisites: Level 1
Benefit: If you are adjacent to an ally who also has this feat, as a swift action, you may give that ally a +4 circumstance bonus to their AC, in exchange for taking a -2 penalty to your own AC. The bonus and penalty provided by this feat last until the start of your next turn, even if you or your ally with this feat move apart from each other.
If your adjacent ally with this feat wishes to, they can grant the same bonus to you during their turn, assuming you are both still adjacent to each other. This effectively reduces the AC you granted to them down to +2 (since they take a -2 penalty), but also grants you an effective +2 bonus to your AC (after negating your penalty). In this way, you and your partner can strengthen each other, as long as you remain adjacent.
Note: This is a Teamwork Feat, meaning it does nothing unless you and at least one other member of your party each possess this feat.