Welcome to St Francis Folly, the first level of the Greece section from Tomb Raider 1.
When you encounter Pierre you have to inflict a certain amount of damage against him and then let him out of your sight. This will result in him disappearing if you inflict enough damage upon him. If you don't let him out of your sight then it's possible for him to remain and for you to keep shooting him and inflict a much greater amount of damage upon him than what should be possible.
In this video I intentionally kept Pierre within my sight and continuously shot him with the pistols for over 36 minutes. He spent most of the time running around but did also take shots at us. After shooting for 36+ minutes Lara's arms became too weak from holding the pistols for such a lengthy amount of time, resulting in her not having the strength to use anymore healthpacks. Consequently, Pierre ended up winning in what was a very long and drawn out battle.
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