Our take on this concept is that there's less of an actual personified "self" at play, and more that there are two (or more?) modes that one can swap between when fronting. Active mode would be that the person fronting is either thinking about themself or are required to be themself in some way. So for a tulpa fronting, they would probably 99% of the time either be thinking of themself or doing something that involves or requires them. For example, me writing this post under my own account requires me (though I'm a little blendy with Piano since he just eats this sort of theory stuff up), since it's my account and my "voice." It's the active me doing this, actively being me or thinking about me.
If I were to have to do something completely unrelated to me and/or I stopped thinking of myself while doing it, the brain would want to go into a passive mode. However... it's harder for a fronting tulpa to go into passive mode if they're only possessing and not switched. To cut the extra baggage, it defaults to the host's passive mode, since he's still the one switched in. If we're continually doing something that really doesn't require a particular person and just needs someone to get it done, it will typically remain Radio's passive mode doing it, even if we go "hey I'm supposed to be fronting here."
And that's why fronting feels like an uphill battle a lot of the time. We can't just passively front, we have to be actively required or actively thinking about ourselves. If we can get more of a passive mode going for us, that would be a step towards actually switching. The brain wouldn't have to default to Radio's passive mode, it could go to ours instead.
Passive mode for Radio seems to come in a least two flavors that we can identify. The first would be task-focused. We want or need something done (and that thing doesn't explicitly require any particular person to do it), so Radio's passive mode comes out to do it. This can be anything from listening to a lecture at school to just walking to a certain location on campus. If we're not making a conscious effort to maintain our own active modes, Radio's passive mode comes in.
The other passive mode is less task-focused and more just what happens during idle moments where nobody's active mode is present. Standing around at work. Sitting around at home. Watching YouTube videos. These are all idle activities that don't explicitly require a tulpa, so Radio's passive mode starts up.
I think if we were to develop our own passive modes, we should think about breaking it into the two categories: task-focused and idle-existence. What does passive Indigo do when he's focused on a task? What does he do when he's just standing around? I think that sort of thinking might be a good place to start. Other than that, working on having our active mode on as much as possible might lead to the development of more of a passive mode that doesn't default to Radio. Meditating on trying to get Radio's passive mode to calm down could maybe also work, we'll just have to see.
The main idea is that if a fronting tulpa can maintain a passive self during task/idle moments, the host's passive self would have less opportunity to come in, which could help build up more and more consistent fronting for the tulpa and less and less activity for the host. Eventually, perhaps, the host could take an inactive mode, and the switch would occur.
We like this theory because it does seem to put a lot of pieces together in a way that makes sense and answers a lot of questions. Even if all the terminology here like "passive mode" or whatever is a little much, I think in the end the methodology to it might be a big help to actually cracking the switching puzzle.