Each time you fight a story battle on the side of one of the three potential heroes - Cao Cao, Liu Bei, and Sun Jian - you'll gain a Contribution to their cause. Only a few Contributions are ...

Xu Shu, who is much humbler than Pang Tong or Zhuge Liang, joins Liu Bei's army because he deeply believes in the hero's cause, but is quickly blackmailed into switching to Cao Cao's side instead.