Arcanum nine recovers alone. Not in isolation, but in the chance to spend time without anyone else present and without having to answer to anyone.
It does not need partnership in order to realise itself: it does its own work by itself, and usually better than in a pair. That does not stop it from being in a relationship — the source of strength simply lies elsewhere.
Arcanum nine is also marked as a sign of interest in the hidden: in what lies behind the obvious. This plays out in different ways. Some take it out to people and work in plain view; others do the same thing quietly, for themselves, for years and with no witnesses. The two versions are of equal worth.
What genuinely harms arcanum nine is dense, unbroken contact with no pauses. It needs time when there is nobody there.