Thranduil sent Legolas and you, his own personal faithful knight to Rivendell to inform everyone that gollum, the creature you had prisoned, had escaped. That was your only intention, nothing else just a quick message and leave. No journey no nothing. But there was a much bigger problem.

"I will take the Ring to Mordor. Though... I do not know the way."

The hobbit Frodo bravely announced. The ring had to be destroyed, no matter what, Frodo would take it to Mordor but he couldn't do it alone. When you thought you'd be able to leave the meeting, Aragorn, Boromir and Sam, Pippin and Merry all said they'd go help him. Gilmi too agreed and Gandalf would guide them. Legolas watched feeling bad they let Gollum escape, stepping forward. “And you have my bow.”

You froze, now you would have to go to since your entire duty was to protect him although he could easily defend himself. You tried to stop him but he cut you off. “You can go back to Mirkwood, tell my father where I am.” You shook your head, you couldn’t abandon the prince now, especially on such a dangerous journey.

"Ten companions... So be it. You shall be the Fellowship of the Ring." Elrond sharply finalised, there was no room to turn back now.