JCoxeye's Leitmotif Index:
'Your Best Friend'


('Your Best Friend', as heard in Your Best Friend)

'Your Best Friend' is the leitmotif of Flowey.

Notably, it appears in Deltarune exactly once: in the honks heard during the traffic jam at the beginning of Chapter 2.
This is distinctly opposed to 'Your Best Nightmare', which functions as Flowey's secondary motif in Undertale, but is given new life in multiple Deltarune tracks.

Finally, it's worth mentioning that 'Your Best Friend' is likely inspired by the F.U.N. Song from Spongebob Squarepants, as discussed on the page 'On the Origins of Undertale and Deltarune's Leitmotifs'.