I am proposing character designs with expression and fluidity in mind. Jack Valentine himself incorporates love heart iconography, which is echoed throughout his attire, and a colour pallet that links him to the classic aesthetic of Valentines Day. 

I have also drafted a version of the poem that will form the basis of the piece. Likely to be spoken over subtle music track that will incorporate a door knocking sound effect as a key motif. 

Knock knock, run,

Kids to the door.

There's nothing there? 
But.. gifts, on the floor...

A collection of goodies,

A pile, a stack,

But inside or outside,

There's no sign of Jack!

He tumbles and twists,

He clambers and climbs, 

He hides around corners,

Until there's no sign, 

Of Jack Valentine Man, 
With his sweeties and tricks, 

Left on the doorstep,

of kids who run quick!

In Norfolk he prowls,

On February 14th...

Until his tricks are all gone,

And his gifts are bequeathed.

Knock knock, run, 

Kids to the door.

This could be his last!
You can never be sure...