- B et ween ▁is ▁also ▁the ▁place ▁where ▁strange ▁mult id im ensional ▁be ings ▁dwell . ▁In ▁any ▁case , ▁these ▁zones ▁aren ' t ▁really ▁understood . ▁ ▁Walk ers ▁Walk ers ▁are ▁special ▁people ▁with ▁that ▁poss esses ▁the ▁gift ▁of ▁" walk " ▁through ▁real ities . ▁So ▁far , ▁the ▁only ▁known ▁Walk ers ▁are ▁Joseph ▁H ark er ▁and ▁all ▁of ▁his ▁alternate ▁counter parts . ▁ ▁Char acters ▁ ▁Inter World ▁▁ ▁Joseph ▁" Jo ey " ▁H ark er : ▁The ▁main ▁hero ▁of ▁the ▁series . ▁He ▁is ▁a ▁ 1 6 - year s ▁old ▁student ▁who ▁discovered ▁the ▁ability ▁to ▁" walk " ▁between ▁real ities / dim ensions . ▁ ▁H ue : ▁A ▁" m ud l uff " ▁( MD L F , ▁short ▁for ▁" Multi - Dim end ional ▁Life - Form ") ▁that ▁res emb les ▁a ▁soap ▁b ubble . ▁It ▁becomes ▁attached ▁to ▁Jo ey ▁after ▁he ▁fre es ▁him ▁from ▁H EX . ▁ ▁Jay ▁H ark er : ▁A ▁very ▁professional ▁agent ▁of ▁Inter World ▁who ▁was ▁killed ▁trying ▁to ▁protect ▁Jo ey ▁from ▁a ▁giant ▁M ud l uff . ▁ ▁Joe ▁H ark er ▁/ ▁The ▁Old ▁Man : ▁The ▁oldest ▁Jo ey ▁in ▁Inter World , ▁possibly ▁the ▁first . ▁He ▁has ▁an ▁artificial ▁eye , ▁which ▁is ▁a ▁Binary ▁construct ▁of ▁metal ▁and ▁glass . ▁It ▁may ▁have ▁many ▁powers ▁the ▁reader ▁is ▁una ware ▁of .