Sirius & Orion are a single Warframe split into two playable brothers, and the game asks you to mark one of them as the primary son. That label is more than flavor. It decides which frame you control when a mission starts, where Helminth abilities go, and which brother your equipped gear sticks to. Picking the right one keeps your build tidy, even though you can swap the designation later.
Quick answer: Pick Sirius as the primary brother if you intend to infuse a Helminth ability and want a defensive opener, since Helminth and your gear are locked to the primary son. The choice is not permanent, though. You can change which brother is primary at the Pontis Tower after finishing Jade Shadows: Constellations.
What the primary brother changes in Warframe
Sirius and Orion share one Warframe slot but keep separate upgrade screens, so each can run its own Mods, Auras, and Arcanes. The primary designation only affects a handful of systems, and those systems are the ones that matter for building. The uncontrolled brother becomes an invulnerable AI ally that fights and casts on its own, similar to a Specter.
| System | How the primary brother affects it |
|---|---|
| Mission start | You begin every run controlling the primary son; the other becomes the AI wingman. |
| Helminth | A subsumed ability can only be infused onto the primary brother. |
| Gear | Your equipped gear is usable only with the primary brother. |
| Duviri | Only the current primary brother appears in Teshin’s Cave for randomized loadouts. |
| Hubs | The secondary brother is absent from Relays and the Base of Operations. |
| Shared between both | Archon Shards and Decrees apply to both brothers. |
By default, Sirius is the primary brother if you buy Sirius & Orion with Platinum. Otherwise the primary son matches the name you chose at the end of Jade Shadows. Either way, the pick is recoverable, so treat it as a starting preference rather than a final commitment.
Why Sirius works well as the primary brother
Sirius leans into survivability, which makes him a comfortable frame to open a mission on. His Light’s Sanctuary creates a growing dome that heals allies, reduces incoming damage, and revives anyone who enters bleedout inside it. Jade Stars summons motes that fire at enemies for Heat damage, and Coronal Ejection throws a returning scythe that scoops up pickups on the way back.
Because Helminth infusion only lands on the primary son, Sirius is the natural home for a subsumed power like Roar. Players who run a damage-focused setup often install Roar over Coronal Ejection on Sirius, then stack Ability Strength on him so his version of Celestial Clash hits hardest. Keeping Sirius primary means that infusion stays where your strength is concentrated.
Why you might leave Orion as the secondary brother
Orion is the aggressive half of the pair and tends to feel strong without any Helminth help. Gravitic Slash performs a wide frontal cut that deals Slash damage while stripping a portion of enemy armor and shields. Event Horizon throws a drifting black hole that ragdolls and pulls enemies together across a large area, setting up clustered targets for big damage.
Since both of those abilities already pull their weight, many builds leave Orion’s kit untouched and let him serve as the wingman or the brother you tag into for control. That frees the single Helminth slot for Sirius without sacrificing what makes Orion useful.
How to change the primary brother after Constellations
Note: A subsumed power gives you both brothers’ second abilities, but you can still only infuse one Helminth ability, and it lands on whichever son is primary at the time. Set your primary brother before you infuse so the ability lands where you want it.
There is no wrong answer here. Sirius makes the cleanest default because his defenses ease you into a run and his strength stacking pairs with a Helminth infusion, while Orion stays strong as the wingman you tag in for armor stripping and crowd control. If your build shifts, the Pontis Tower lets you flip the primary son whenever you like, so commit to one now and adjust as you learn the duo’s rhythm.
