This Route is on the W/SW face of the Sibling, essentially on what would be considered it's back side. The best approach to this is either up to the North side and then up around to the West, or going West until parallel with the top of the rock and slightly above, then dropping down into the West face from the South.
This climb starts from near the Northwest Arete. Step right (South) onto the center of the West face and diagonal up and right a few feet to a crack and corner system. Follow a right-facing corner up to a roof formed by a huge chockstone. Protect on good gear, and stem up and through the roof to more good crack- climb that to reach the tree at the top of the ridge, and the fixed anchor in place there.To descend, rap from the the fixed anchor.
A standard light rack. 1 set stoppers and cams.