To befriend someone is easier when you do it with tenderness.
But you should use it frequently with any old friends or any social interaction for that matter.
Try a little tenderness. Be more intimate. Ask more questions. Be there for them.
People might be in urgent need for someone to be tender with them. But they might be hiding it, thinking they might humiliate themselves.
If they need it, you should be the friend that helps. Not the one that mocks or ignores.
If they don’t seem to need it, you should still try occasionally to have a serious talk, or go deeper into a problem, or simply show up when they don’t expect you to.
Such friendship can grow exponentially and create an unbreakable bond.