Charles Forstman is a billionaire with a bad reputation of being a shady and manipulative banker.
History
Not much is known of Charles Forstman's early life, but he is known to be very shady and engage in illegal activities. He had a deal with Harvey Specter's father once, a deal both Harvey and his younger brother Marcus were aware of. When Harvey won a case as the Assistant District Attorney, he was approached by Forstman who offered him a job, but Harvey refused based on his bad reputation, a reputation that Donna Paulsen was easily able to find out about online and one that Jessica Pearson was aware of as well.
When Marcus Specter asked Harvey for $150,000 to open a restaurant due to the fact that he was unable to legally ask for a loan (Marcus being a degenerate gambler) Harvey told him he couldn't because he only made $50,000 a year as an Assistant District Attorney. Marcus then told Harvey that if he couldn't loan him the money then he would ask Forstman for it, so Harvey wound up asking Jessica if she would hire him. Jessica, however, wanted Harvey to work under District Attorney Cameron Dennis for a few years and refused to hire him at Gordon Schmidt Van Dyke, which prompted Harvey to accept Forstman's job offer.
Forstman told Harvey that since he suddenly wants the job he would have to explain why, with Harvey telling him Marcus needed $150,000 to open a restaurant, and that the restaurant was a chance for Marcus to make something out of himself, since he had gambling issues. Forstman offered to hire Harvey if Harvey could beat him at a race, as Forstman owns his own private race track as well as his own assortment of cars. However, at the race track, Forstman talks poorly about Cameron Dennis and the individual on his opposing case, and Harvey backs up Cameron and tells Forstman what's going to happen to the man involved in Cameron's case. Forstman hires Harvey on the spot due to the fact that Harvey was loyal to his employer, something he looks for in his own employees.
However, since Harvey had told him what would happen to the man involved in Cameron's case, Forstman ended up selling all the shares he owned of that man's company, which allowed Forstman to make over $100 million. Harvey, upon finding that out, was enraged that Forstman did such a thing and threatened to report him, but Forstman told Harvey that since he was the one who told him what would happen, Harvey would end up in trouble as well. Forstman gives Harvey his signing bonus check but instead of a million dollars, it is for $850,000 - Forstman telling Harvey that he gave the other $150,000 to Marcus to open the restaurant, and that if Harvey really wanted to report him, not only would he implicate himself, but Marcus would also lose the money and therefore won't be able to open his restaurant, and would probably spiral down to gambling again. Not willing to do that to his own brother, Harvey drops the matter at hand and returns to working as the Assistant District Attorney.
Several years later, Mike Ross approached Forstman for money in order to save Gillis Industries from a hostile takeover by Logan Sanders and his company. Harvey, who was Logan's lawyer, told Mike not to go to Forstman, telling him that Forstman doesn't care about money as much as he does controlling people, but Mike disregards him. However, Forstman only offers Mike the money if he agrees to cut his boss Jonathan Sidwell out of the deal. Mike agrees, but ultimately is unable to do so and does not take the money. Forstman then alerts Sidwell that Mike had agreed to the deal, which leads to Mike being fired from Sidwell Investment Group as well as costing Walter Gillis his company.
Forstman is also approached by Louis Litt, who tells Forstman how much he wants to solve this Gillis Industries ordeal for his firm and one up Harvey. Forstman agrees, but only if Louis funnels the money through Switzerland and the Cayman Islands therefore as to evade paying tax. Also, he makes Louis take $1,000,000 out of the deal to keep him from turning on him. Louis, not wanting to go tell Harvey and Jessica that the deal would have to be cancelled, agrees, potentially implicating Louis as he is now guilty of tax evasion.
Forstman offers Mike a job with a million dollar signing bonus, but before Mike can accept the job, Louis sees him on his way out and rehires at Pearson Specter, to protect his tax evasion secret as well to prevent Mike from working for someone like Forstman.
When the firm is later aggressively pursued by the U.S. Securities and Exchange Commission. headed by Sean Cahill, it is revealed that Cahill's boss, the head of the S.E.C. is none other than Eric Woodall, a former U.S. Attorney fired for malicious prosecution against Harvey and his firm, and that it was Forstman who had Woodall hired as the head of the S.E.C. - in return, Woodall would protect Forstman, which is why Harvey was unable to threaten to report Forstman for his tax evasion. Harvey, Louis and Mike come clean to Sean about Louis' involvement in the tax evasion, but also tell Cahill that the person he should be going after is Woodall himself, and that proof that he is on Forstman's payroll would be in Woodall's bank accounts.
In order to protect himself, Forstman had the money he gave to Woodall used to have Woodall's first wife, who has Alzheimer's, moved into a private facility with round the clock medical care. Mike and Rachel are able to figure this out and tell Harvey, who asks Woodall to turn on Forstman. Woodall, angry that Harvey found out about his ex-wife and was trying to use her to make him turn on Forstman, runs to Forstman, who comes to Pearson Specter Litt to talk to Harvey. However, Harvey had Sean Cahill secretly follow Forstman and was wearing a wire during his conversation with Forstman, much to Forstman's surprise and indignation, in which Forstman implicated himself and confessed to his illegal activities, which allowed the U.S Marshals to arrest Forstman.
Season 5
Forstman, who was incarcerated, managed to use his money and his influence to remain in a cozy prison, where he was free to walk around with a jumpsuit and play pool. Harvey goes to visit him when it becomes obvious that Forstman is funding Daniel Hardman's coup against Pearson Specter Litt; however, Forstman only agrees to cut off Hardman's funding if Harvey resigns from his position.