RainbowSixSiegeFan here. Sledge origin story. Let's begin
Sledge's Knock
"Hrrummph" Seamus "Sledge" Cowden grunted as he broke the wall with his hammer, creating a new entry into the heavily fortified base of the university-turned-base for the infamous White Mask terrorist group. He let the faster operatives such as Eliza "Ash" Cohen and Monika "I.Q." Weiss run in first before coming into position with other more bulkier ops such as Michael "Thatcher" Baker and Gilles "Montagne" Tourres come in. Sledge raised his L85A2 and started firing rapidly at the exposed terrorists. Asmathic breathing could be heard and Sledge recognized this as a Suicide Bomber. He quickly threw a frag, and after a second, a large boom could be heard, and then a large thud and a "oomph". Sledge smiled but realized the oof wasn't from the bomber, it was from Monika, who had sustained an injury. He slowly came over and treated it, while Tourres and Baker covered fire. Sledge treated her arm while flashbacks from a time very long ago came back...
Seamus was very athletic in the SAS. He had completed both the 500 meter run and bench press competition was record speed and superior strength. His only problem, however, was with sledgehammers. He could never break a wall, let alone a door with it. He aced everything, but when it came to the hammer, his usually awed mates and trainers were disappointed. Sledge would try constantly but it never worked. It got to the point he was going to quit the SAS due to not being able to try. The day he decided he would leave, A lady walked in to the HQ. She introduced herself as Six and stated there was a competition for the best agent there, and the winner would get a prize. Sledge decided to compete.
Sledge dominated the speed, strength, marksmanship, and intelligence components. The final part was infiltration, search and rescue, and exfiltration. Sledge completed the first half and then, was left to Sledge and Mason Arthorn. Mason was a bully and a rival to Sledge who always mocked him on his ability to use the hammer. This time however, Sledge would win the competition. Mason wnent first, using a hammer to mock Sledge. He hit the hammer and the door fell down and he went in, rescued the fake hostage, and got out. Then it was Sledges turn. He got the hammer and hit the wall. No effect. Sledge turned to a disgruntled Six and asked for a retry, to which Six allowed. He hit the wall again. No effect. Sledge could hear Mason laughing and asked for a retry. Sledge prepared his hammer. Here goes nothing, he thought. He hit the wall so hard the wall and connecting walls fell down, destroying the impromptu base. Sledge walked in the rubble and got the fake hostage and sheepishly gave it to Six, much to the surprise of Mason. Six took it in shock and said "Welcome to Team Rainbow"