Coran was the royal advisor for the royal family of planet Altea, serving King Alfor even during the king's expeditions. He was placed in charge of the king's daughter, Allura, when Alfor decided to hide the Voltron Lions from Zarkon and place Allura in a deep sleep. It is not until 10,000 years pass that both Coran and Allura awaken from their stasis, appearing to be the last Alteans left alive in the entire universe.
He has an eccentric personality that can come across as bizarre to the rest of his teammates, which is not aided by his Altean culture and literal alien language. However, Coran is highly protective of his team, especially when it comes to Allura.
Coran has shown little to no combat abilities, but his gift is immense encyclopedic knowledge about the universe, if perhaps 10,000 years outdated, which allows him to act as a guide and source of wisdom for his team. Unlike other Alteans, he has no alchemical proficiency and no ability to channel and harness Quintessence.
Coran explains that the Castle of Lions is 10,600 years old by the time the human Paladins arrive on Arus, and states he was alive at the time his grandfather was building the Castleship. This places Coran's age around 600 years old at the very least.
Being 600 years old is considered "later in life" or old for an Altean, as Coran suffers a case of "the slipperies", which is a common virus for older Alteans. Coran is noticeably in denial about his age.