Well, do as you please. Shout if something is up... To hell with you, Rambo wannabe!Petruha to the player if he decides to clear the car park without Petruha's help.
A short bio, which describes him as follows: 
Shadow of Chernobyl
In the beginning of Shadow of Chernobyl, he is tasked with leading the attack on the Car Park and questions whether to attack the park head on or let the Marked One do it himself. He carries a sawn-off double-barrel shotgun.
Petruha can first be found with two other loners on a hill just southwest of the Car Park in the Cordon during the Kill the Bandits at the Car Park mission. After the vehicle station is taken, Petruha will idle by the fireplace in the main building there. Because Bandits will constantly attack the park, Petruha is usually killed due to his low quality equipment (although this isn't canon as he later appears in Call of Pripyat).
Call of Pripyat
Petruha plays a minor role in S.T.A.L.K.E.R.: Call of Pripyat as one of the Skadovsk Loners. He can be seen in the Boiler Anomaly hunting for artifacts with his friend Awl. Both of them have been saving money for a new suit but the only thing they could buy was a Sunrise suit. Then if the player stays long enough, Petruha will get hit by the anomaly. If the player chooses to help him, he'll give his Bear detector as a reward, or a Fireball if the player already has a Bear Detector or a better one equipped. After being rescued, Petruha and Awl will wander around the Zaton area like a normal Stalker squad. He will most likely eventually die after a few random run-ins against Bandits or Mutants, but if you run into his partner after his death, he will still thank you for saving Petruha.
Shadow of Chernobyl
- This character is known for occasionally carrying the beta bag item Binoculars. With patch 1.0005 he will sell the Binoculars for 199 RU.
- If you decide to take over the vehicle park and rescue Nimble without any assistance from Petruha's squad, Wolf will give you a better reward: a Fort-12 pistol, 2 RGD-5 grenades, 1 F1 grenade and some ammo and medical supplies. Petruha himself will stand at the same place overwatching vehicle park for the entire game if nobody kills him.
Call of Pripyat
- If one is feeling rather evil (or opportunistic), the player can kill Awl to loot his body and although Petruha will become hostile and thus cannot be saved, he can also be killed and both his Bear detector and Fireball artifact can be obtained.
- Once after Petruha is incapacitated, his MP5 can be taken away without any penalty.
- Neither Petruha nor Awl can be healed with a medkit if they are wounded. If the player tries to help them, they receive the same dialogue thanking them for saving Petruha, and the option to give either a medkit isn't available.
- After being rescued, Petruha and Awl might not travel together anymore, instead they might be later seen joining different squads.
- Sometimes when trading with Petruha, one can purchase a First-Aid Kit from him which does not stack with other conventional First Aid Kits because it says it has no effects then being worth 75 RU less. He also carries a PDA which can be dropped and has no information on it. (This happens to random NPCs in the game.)
- Despite the fact that Petruha's bio describes him as a rookie, he is actually of Experienced rank.
- In Call of Pripyat, Petruha is referred to as Petrukha by Awl in the dialogue, although game interface gives his name as Petruha.