Even now, Spock wished there was something he could have done for Sybok, someway to reach him before he was lost in a path of no return, where his only shot of redemption came at the cost of his own life.

In truth, they had never been particularly close, perhaps because they hadn't spent their early childhoods under the same roof, or perhaps because as a full Vulcan Sybok was permitted some freedoms that Spock would never enjoy, being always judged for his human half, and so having his feelings policed to a greater level than any other Vulcan, to his detriment and in a way that would have lasting and damaging consequences that he needed decades to overcome, so perhaps he had resented Sybok, both for being freer than he would ever be and for his emotional outbursts that lead to his banishment but also made so that Spock was watched with even greater scrutiny, for fears that he too would follow on the path of their ancestors and abdicate his emotional control.

Sybok was the worst brother he could have had, but he was still his brother, and so, despite their differences, Spock wished he could have saved him.