Lifegiver

Livegiver is a Fallout, Fallout 2, Fallout Tactics and Lionheart Perk.
 * Requirements: Level 12 (11 in Lionheart), EN 4
 * Ranks: 3 (Fallout) or 2 (Fallout 2, Fallout Tactics, Lionheart)
 * Benefit:
 * With each level of this Perk, you gain an additional 4 (6 in Lionheart) Hit Points. This may not seem like a lot, but every little bit helps. (Fallout)
 * Everytime your character gains a level, gain an additional four Hit Points for each rank of this Perk. With two ranks of Lifegiver, that’s +8 HP each level! (Fallout 2)
 * Notes: Although it's not clear from the description, Lifegiver gives you +4 HP when you take it; you could say it works retroactively for the level you just earned.