Tracey ♥ Dawn
They are the only ones of Ash’s friends who are only children*.
They are the only ones of Ash’s friends not to be, in some way, related to the Gym Leader position*.
*This is only an assumption as there is no information on Tracey’s family.
Beam is derived from Dawn’s Japanese name and Tracey’s personality. Hikari means light, relative to the term “beam of light,” and Tracey is a positive person who smiles to the point that he often ‘beams’.