This slightly-more-than-a-triangle is cousin to The Peacock’s Tale with the same style of evolving feathers that can each be repeated until you want to transition to the next section.

Here I worked:
1 x set up
2 x first feathers (plus transition)
1 x second feathers (plus transion)
1 x third feathers (plus transition)
5 rows of edging (for the trail of sparks..)

Experimented with a crochet BO for this one, but could just as well have used a normal stretchy BO.

1g remaining after BO. :D

150x60cm (60x24in)

Comfortably more than a triangle as seen in the folded in half pic on the couch.

Now trying to decide if it’s a phoenix or a firebird..

I should mention too that I tried several different eyelet techniques and evolved the pattern as I worked so eyelets in the yellow section will be more like those in the red section in the final pattern.

Afterthoughts

The twisted spine could be swapped for a standard yo, k1, yo, just remember to pick up one less st in the garter tab.

Also with the decreases that balance out the eyelet, you could swap the two decreases used in the first 2 feathers for the single sk2p used in the third feathers and use the sk2p throughout.