Antespace is the dimensional mindscape created when a combiner forms. Disparate personalities must put aside their differences and unite their wills for the combiner to be effective in performing even basic physical acts. However, a more disciplined, rebellious or damaged individual mind can unduly influence the whole, seizing control of the combined entity with unforeseen and often destructive results.

In some cases, the more time a group of individuals spend in antespace together, the more connected in purpose and similar in personality they can become outside it. If one of the team dies, their "ghost" can even still linger in antespace, leaving echoes of themselves in the minds of the remaining members.

Fiction

2005 IDW continuity

After Scrapper was killed by Spike Witwicky, a trace of his consciousness still lingered in antespace and sometimes manifested when Devastator formed. This aspect haunted Prowl and filled him and the surviving Constructicons with a desire for revenge on Spike. Signals, Calls, and Marches The Obliterati

Antespace makes Bumblebee's face weird.

When Prowl used the Enigma of Combination to merge himself, Optimus Prime, Ironhide, Sunstreaker, and Mirage into Optimus Maximus, he used his familiarity with antespace from his time as part of Devastator to try and take control of the new entity. However, Optimus Prime quickly rallied the others and they collectively convinced Prowl to meld minds and work together. All That Remains Afterwards, Optimus and Prowl came to blows, and Prowl claimed that a trace of his mind would always remain within Prime's thanks to their shared time in antespace, even if Prime killed him. Now and On Earth

The Combaticons later used the Enigma to merge into Bruticus, with Onslaught hoping to use antespace to pry into the then brain-dead Swindle's mind. Their dissonant focus within the shared mindscape resulted in Bruticus going on a rampage in Iacon. The Line Between Us

After Optimus Prime and Bumblebee's bodies were destroyed and their minds trapped in infraspace, they managed to escape into an antespace pocket within Pyra Magna's mind. With both Optimus and Pyra already familiar with antespace and united in purpose to defeat Shockwave, they suffered no disharmony despite the tension Bumblebee sensed between them. Unforgivable

Notes

• While the concept of a combiner's merged mindscape was explored several times in the 2005 IDW continuity, it wasn't given an official name until Optimus Prime #21.