Well, yes and no… :winking_face:
When you say ‘using lookup’ you’re skipping an intermediate step: Namely, the creation of a link between records of two (usually; see below) tables using a linked-record field. A lookup field essentially follows a link from the current record to one or more linked records and retrieves the value or values of a specified field in the linked record(s).
Typically, one uses a lookup field when trying to retrieve the value of a field other than the primary — first — field of the linked record. This is because the linked-record field itself contains the value of the linked record(s) primary field(s). That is to say, if I have a linked-record field named {Link2Color} in my [Main] table, and the current record of [Main] is linked to records ‘Red’ and ‘Blue’ in my [Color] table, the value of {Link2Color} in my current table would be ‘Red, Blue’. I could create a lookup field that followed the link specified in {Link2Color} and retrieved the value of the linked records’ primary field — but as the result would be ‘Red, Blue’, doing so would be a redundant step.
When I indicate a linked record from [Main] to [Color] by creating the link in {Link2Color}, I automatically create a reciprocal link from [Color] to [Main]. (By default, that reciprocal link carries the name of the linked-from table, so in this case each record in [Color] would have a linked-record field simply called {Main}.) I can use this reciprocal link as I would any linked-record field; for instance, to display a list of all [Main] records linked to the ‘Red’ record in [Color].
In the case of Sam and Jack, then, you could link from ‘Sam’'s {Link2Enemies} field to ‘Jack’'s record and have a reciprocal link created automatically from ‘Jack’ to ‘Sam’…
…except there’s a catch.
Earlier I said one usually created a linked record between records of two different tables. It is also possible — and, from your description of your base, it seems applicable to your use case — to create links between records of the same table. That is, ‘Sam’ and ‘Jack’ would both be records of, say, your [People] table, and ‘Sam’'s {Enemies} linked record field would link to ‘Jack’'s record in the same table. In such a case, Airtable does not create a reciprocal link. ‘Jack’'s record would contain an {Enemies} field, and it could be linked back to ‘Sam’, but the link would have to be created manually: It won’t be created automatically.
Why this is the case, I’m not sure — you can convince me either decision (to create or not to create a reciprocal link) is correct — but it is Airtable’s current behavior.
I hope that explanation wasn’t too convoluted; if I stumbled around to much let me know and I’ll give it another try…
