Damon Baird is initially a member of Alpha Squad (who were given control of the resonator near the beginning of Gears of War.) After many of their squad died, including Rojas, he was designated to join Delta Squad after the death of Lt. Minh Young Kim. Although angry that he was not given command of Delta Squad after Kim's death, he does eventually become loyal to Marcus Fenix throughout the the course of the game.
Baird is considered by many to be an extremely capable soldier who is constantly promoted, but then busted back down for insubordination, disagreeing with his superiors and generally being unpleasant.
Baird has strong knowledge of the Locust Horde from viewing their strategies on the battlefield. He is also an expert in mechanics and engineering, and this is demonstrated by his hacking of a geobot at the end of ACT 3 when he finds maps of Locust tunnels. He also fixes the Junker in ACT 4, which is used to escape from a rampaging Brumak. Additionally, he also deploys the sonic resonator (ineffectively) at the end of ACT 3.
Baird's cynical tone is an entertaining foil to the boisterous attitude of squad-mate Augustus Cole.
In Gears of War 2, Baird is more accepting of Marcus' command of Delta Squad. He is seperated from the rest of Delta Squad while fighting underground after his grindlift is captured by the Locust. Dom, Marcus and Cole eventually free him. Fighting alongside Marcus, Dom and Cole, Baird helps to bring down the rockworm from the inside. During the attack on the secret research facility, Baird keeps Delta Squad's Centaur tank in working condition while making an explosive device for Marcus and Dom. He is then involved with going underground with the rest of Delta Squad when they learn of a Locust "Nexus" where Locust forces are amassing, under the Kadar Mountains. Marcus orders Baird and Cole to use the Centaur tank to evacuate the rest of the Stranded to the surface, await the beacon and arrive in grindlifts. Baird lets Marcus know of his reluctance to do this, and worries about letting Marcus and Dom go alone and find the Nexus on their own.
The four are all reunited when Dom and Marcus activate the grindlift beacon through Jack, and after a series of furious firefights, find themselves in the Locust Throne Room where they are confronted by Skorge and the Locust Queen. The Queen orders all four of them to be killed, and Marcus orders Baird and Cole to pursue her while Dom and Marcus take on Skorge. The four manage to escape on stolen Reavers and head towards Jacinto, while fighting several Locust atop Reavers, and finally Skorge atop his Hydra. In the ensuing fight, Skorge is killed.
Baird is involved in the fighting in the defense of Jacinto, and once the sinkhole appears above the pool of Imulsion in the middle of the city, Baird and Cole arrive via King Ravens. Baird informs Marcus that the chopper carrying the Lightmass Bomb was knocked down by the Lambent Brumak. Marcus realizes that the Brumak is as explsoive as the Lambent wretches they came across before, and using the Hammer of Dawn, they blow up the Brumak and sink Jacinto and all the surrounding sea water into the Hollow, seemingly decimating the Locust forces.