let them get intimate alone first

You swallow hard and nod at the twins’ offer. You'd like them to ease into this relationship, and working together first should help them out. It’s too amazingly tempting to see the twins handle each other like that, and you don‘t know if you‘ll be able to stop yourself once you start pleasing them.

Nanika runs her slender fingers over Akane’s arms, slipping under them and caressing their way down her slender sides. Akane cooed appreciatively, melting in her sister’s arms and leaning into her attentive hands. Nanika’s hands wound up cupping her bottom firmly, making Akane let out a loud gasp of pleasure as her legs gave way, collapsing into her Nanika’s grasp.
She giggled and kissed her sister’s neck, Akane purring softly in a nearly dreamlike state. Her eyes flutter as her wings twitch gently behind her, fully supported by Nanika as her kisses go lower, trailing down her throat and collar bone, bringing her hands around her waist and slipping her hands down her belly. Nanika slid down to her knees, better supporting Akane as she slid into a near submissive coma. She settled her face on Nanika’s modest breasts, panting breaths and quivering lips brushing over her nipples.

Nanika’s own blush begins, but she cups both of Akane’s tender little tits and lifts them upward, massaging one as she takes the other and starts to suckle on her nipple, eyes looking up straight at you in a mix of teasing and pleading for approval.

You’ve already got your manhood out, rock hard and stroking it slowly at the unbelievably erotic sight.