Use this strong and secure knot. This is a midline loop and you can tie it anywhere in the line.
To Tie an Alpine Butterfly Loop:
Wrap three turns around the non-tying hand.
Whether left or right-handed, lift up the turn closest to the thumb and replace it close to the finger tips.
Do the same again but continue by drawing the bight through-back toward the wrist- beneath the other two turns.
Pull the resulting loop into shape and tighten.