Hachure
Pairing - NxU
Hachure - : to shade with or show by short lines used for shading and denoting surfaces in relief (as in map drawing) and drawn in the direction of slope
She didn't draw old maps; they were inaccurate. The traditional methods of contouring were inefficient compared to new standards, though she would admit they did look impressive. Tiny lines, hachures shading the area to signify the steepness of the hill. It made the whole map seem shaded, and while Nami appreciated the beauty, it didn't make it easy to read.
He didn't draw maps; the were confusing. But in a roundabout way he did know about the old fashioned methods of shading, and he was a big fan. It made a simple sketch look far more impressive. Tiny lines to highlight the shadow caused by the light over the desk, longer lines darkening the swirling pinwheel as the arm eagerly moved to draw the next line, and the lips shadowed as they pursed in concentration. It brought body and life to a sketch, and Ussop hoped Nami would appreciate the beauty.
When Nami saw her gift, she thought she should try writing old maps more often.
Though I am not a fan of the hetero pairing in OP (I like my fanfics with Yaoi, thank you very much!), there are 2 pairings I do enjoy. UxN is one of them. They are both quite...human compared to the rest of the crew. They fear more and they try their best to be brave despite not being inhumanly endowed with powers or strength. They are also smart and I just think they go quite well together. So as soon as I learnt what Hachures were I immediately envisioned Ussop drawing Nami. They are just too cute.