All-New Marvel Now
Before becoming a member of the new Euroforce, Franco Fibbri was a famous soccer player, stated as "the most paid soccer player in the world".
When he retire, he spent all his money on a dangerous project to imbue himself with strange and unidentified alien substance which transformed him into the golden compound being. He take the battle name of Sliver.
When a tv show ask him why he have chose to undergo this transformation, he state that he was bored of anyone asking for his money for aiding children: now he have no more money, he used them to become a superhero (he may or maybe not joking).
He was then made a member of the new team Euroforce led by the Black Knight, and durring a mission he, along with the rest of the team, fight with some Avengers against Morgan Le Fay and her army of the dead, under the Italian City of Velletri.
Sliver is now made of alien compound that give them a still unclear range of powers. He was able to growth large spike all over his body, suggesting that he may "shapeshift" as some sort of "liquid metal", and also have used his compound to cauterize and partially heal some Hawkeye wounds.
While not still specified, given the mutation caused in the body of Franco Fibbri, may be supposed that the alien substance used on him have some connection with the Klyntar race.