TV show LOST question?

Before Desmond came on the island, there was someone else there. Who was he? Where did he come from? Was he an other? Did he get stuck like desmond before desmond killed him? Was he part of the Dharma Initiative?Also if he was part of the Dharma initiative, why didn't he die when Ben killed everybody?

he was part of the dharma initative

His name was Kelvin and he was a member of the Dharma Initiative."The half-conscious Desmond was dragged from the beach into the Swan, by a man in a biohazard suit who later identified himself as Kelvin. In the Swan, Desmond was told by Kelvin that the outside environment is contaminated by a mysterious sickness, which he may have been exposed to. Desmond then received a vaccine labeled by the Numbers from Kelvin, and was told to inject himself with it every 9 days. Desmond learned the"pushing the button"routine, and watched the Swan Orientation film repeatedly, which raised many questions in his head, most of which remained unanswered by Kelvin. ("Live Together, Die Alone")After two years, Kelvin showed Desmond how to initiate the lockdown sequence, which Kelvin used to complete the invisible blast door map started by his previous Swan partner, Radzinsky. One night later, while drunk underneath Swan's computer room, Kelvin revealed to Desmond the nature of the Incident, and the function of the fail-safe key, which he carried at all times but was never able to find the courage to use."http://www.lostpedia.com/wiki/Desmond_Hume