A, B, or C

A
A held B's hand as C ran away, D consoled E as F started to cry.  G heard from H that trouble was brewing and told I, who was waiting with J for news about K while L fell in love with M.  N went on vacation, and heard that O knew a secret, while P was oblivious and Q made matters worse.  R didn't care about what S told T.  U had hurt V, and V was after revenge.  W was of the same mind as X that Y was up to something, and Z was just trying to help A and B find C.

B
A invited B to dinner at C's house.  There at the dinner, D met E, and the pair became inseparable.  F and G were already in love, and so glad to hear from H and I that J became fast friends with K at the dinner.  L was lonely, but felt better when M was around.  N went on vacation with O's family while P was in the hospital.  Q heard from R about all the gossip, and hurried to tell S, who really didn't care.  T and U got in a fight, V tried to settle it, and W's efforts to reconcile X and Y failed, while Z thought that if A hadn't had the dinner party, none of this drama would have ever happened. 

C
A had a grand plan to get B and C together, but was thwarted by D, who liked to make trouble.  E was oblivious until F got involved and made it a problem for G and H, too.  I was in love, but wouldn't tell J the truth about being in love with K.  L was trying to get the lead, M wanted it, too, so N had to decide, which made O even madder than P had been after the breakup with Q.  R went with S to see T's play, and U took mental notes on how V got along with W.  X just was there, and Y was fed up, but Z was just amused, and finally convinced A that it was just high school.