The best description of Sol-leks’s character based on this excerpt is: He does not seek confrontation, but he is vicious in his own defense.
This is evident from the way Sol-leks reacts to Buck's unwitting approach on his blind side. He does not initiate aggression; instead, he responds defensively and harshly when he feels threatened. After the incident, Buck learns to avoid Sol-leks's blind side, indicating that Sol-leks prefers to be left alone and does not actively seek out confrontation but will defend himself when necessary.