<stdin>

@       you
-       check beam
X       failed beam spawn
*       center
[ p ]   dude
=       grapple beam

This all happens in one tic

@                       [ p ]

STEP 1:

@-                      [ p ]
@---                    [ p ]

etc

@-----------------------[ p ]
@-----------------------X p ]
@-----------------------XXp ]
@-----------------------XXX ]
@-----------------------XXXX]
@-----------------------XXXXX
@-----------------------XXXXX-


STEP 2:

find the two check actors that the enemy is between, remove the rest

@----------------------o[ p ]o
@                      o[ p ]o


STEP 3:

get the midpoint, remove check actors

@                      o[ * ]o
@                       [ * ]


STEP 4:

midpoint check actor does A_LookEx, finds target, grapples

@                       [ * ]    "found [ p ]"
@=======================[ p ]