Players and the Grandfather have agendas and principles to follow. They help enable this game to played in the manner it is intended and improve the play experience for everyone.
You are a freedom fighter, there's no doubt about it. You fight for the freedom to use time as anyone sees fit. The powers that have authority over the web of time that keep it linear and without paradox are both cruel and petty. The are above any laws that anyone cares to think of, even breaking their own in the course of their xenophobia.
In the Spiral Politic - the vast expanse of this galaxy, this universe and even their incursions into the multiverses themselves, the oppressors must be resisted. The imposed theocracy of linear time and the brutal retro-genocides of entire species must be fought. The only reason you aren't fighting for the Enemy is because they are even more fanatically driven and prone to excesses than the Great Houses you also oppose.
You are caught between the opressors that want linear time and the Enemy that just wants to destroy them utterly, trying to have some freedom, some time plurality. You want secular time, free of the fanatic theocrats and their anti-theists and all their brutal ways. No matter the Malevolence you personally incur, a renegade to the old ways is what you'll always strive for.
Your ability to use stress puts you ahead of any antagonist you're likely to come across in the Spiral Politic. don't be afraid to use it whenever possible, only be wary when it approaches levels where you may incur some trauma. With stress you can cheat causality and retroactively solve problems. You will need to exploit that edge in order to hold your own in a vast and dangerous universe.
Be curious about the times and places you find yourself in. Everyone has a story to tell and their own agendas. A medieval peasant with a knife can kill you as easily as a time travelling Dalek if you're not careful. Respect the danger of your surroundings and your place in it.
Planning is the one aspect of the game you need never do in actual play in real time. Not only are your characters gung-ho and impetuous, often leaping first without looking, but they're also competent and will have foreseen circumstances you may not have as a player. Flashbacks cover this as does various other planning moves such as getting gear retrospectively, communing with the spirits or even having to resort to the untethered flashback.
Don't sit down with other players and work our exactly what you're going to do - you never need to. Work out roughly what you are going to do, then do it. Patch up the plot holes if you need to retrospectively. It's why you have stress after all.
You are an anti-establishment, anti-authoritarian renegade existing in a life's worth of time in the eternity of infinity. You are not a cage-farmed chicken or a cubicle worker on minimum wage. You are daring, bold, ambitious and willing to take on the monstrous powers because you actually know they're made of fallible members that really aren't much more impressive than you - individually, often less so. There are reasons why members of Faction Paradox are feared and respected - and it's not just because you can't predict their behaviour.
Everything does not come down to numbers and block transfer calculations. Don't play your character around the numbers that comprise them. You can choose any approach to use with any move but you should always choose the one that matches what your character is doing.
You are as vital a component of the co-operative story you all all creating together as any other player, including the Grandfather. Likewise you have responsibilities for what occurs within the collective fiction. If you want something about your character to appear in the game, you must actively pursue and agenda to have it appear. Your characters strengths and their weaknesses are all worthless unless they interact with the game you are playing and become more than just a note on your playbook.
You are also responsible for your behaviour and the enjoyment of the game by every other player as well. This means your participation effects the tone of the game, the style of play and what themes may occur. When you say something, know what you are saying, and mean what you say.
When commiting to a plan, or a series of actions, go for what you think is fun. Trust in your character's competence to get things done no matter what you decide they do: there are multiple game mechanics to patch over any potential problems that occur. Not only that - you need to know that the Grandfather is a fan your characters, they're the main protagonists, so of course the script is on their side.
When the spotlight shifts in your direction, when the Grandfather or other players look to you expectantly, go for it. Do something cool or something flawed. Try or fail. Show something about your character, something new or something the other players have seen before. Do something that makes sense to you as you get involved in the game.
When attention passes on to others, give them space to shine. Don't rush in with advice and hints, or your ideas on how their actions may fit into your plans. Let them have their moment. Wait until attention is given back to you, or if you are asked by the other players.
For this game, you and your fellow players are a family and need to look after each other. Everyone needs to know they are a safe place so they can roleplay with enough freedom. When you start playing, discuss how you want safety tools to be used to make your gaming experience comfortable and listen to everyone else's contributions. Don't be afraid to revisit the tools every so often. Use them as often as you need to.